Haemolytic anaemia Flashcards
What are some causes of intravascular haemolysis?
Mismatched blood transfusion, G6PD deficiency, RBC fragmentation (metallic valves, TTP, DIC, HUC), cold autoimmune haemolytic anaemia.
Osmotic lysis (occurs with hypotonic fluid as fluid moves into RBCs causing them to burst)
Presents with low haptoglobin (which is what binds free Hb), as it becomes saturated haemoglobin will then bind to albumin forming methaemalbumin
What are some causes of extravascular haemolysis?
Haemoglobinopathies,
Hereditary spheocytosis,
Haemolytic disease of the newborn,
Warm autoimmune haemolytic anaemia
What are hereditary causes of haemoltic anaemia?
Membrane: hereditary spherocytosis,
Metabolic: G6PD deficiency,
Haemoglobinopathies
What are immune acquired causes of haemolyic anaemia
Coombs positive!
Warm/cold AIHA,
Alloimmune (HDN),
Drug induced haemolyic anaemia
What are non-immune acquired haemolytic anaemia causes
Coombs negative - no antibodies!
Microangiopathic haemolytic anaemia (TTP, HUS, DIC, Malignancy, pre-eclampsia)
Prosthetic heart valves,
Paroxysmal noctunral haemoglobinuria,
Malaria,
Dapsone,
Zieve syndrome
What is Zieve syndrome
Coombs negative haemolyisis, cholestatic jaundice and transient hyperlipidaemia associated with heavy alcohol use.
What are the features of haemolytic anaemia?
Anaemia,
Jaundice,
Splenomegaly,
Raised LDH (enzyme found in RBCs), reticulocytes, low haptoglobin and high bilirubin
What are the investigations for haemolytic anaemia?
FBC: normocytic anaemia
Blood film: Schistocytes (fragments of RBCs)
Direct coombs test: Positive in autoimmune haemolytic anaemia
What are the features of hereditary spherocytosis?
Autosomal dominant condition causes fragile, sphere shaped RBCs which break down easily passing through the spleen.
Presents with anaemia, jaundice, gallstones and splenomegaly
What is a complication in hereditary spherocytosis and how does it present?
Aplastic crisis due to parovovirus. Presents with raised MCHC, raised reticulocyte could and spherocytosis.
Investigation - EMA Test
WHat is the treatment for hereditary spherocytosis?
Folate supplement, blood transfusion, splenectomy and cholecystectomy if persistent gallstones
What is another RBC membrane defect which can cause haemolysis?
Hereditary elliptocytosis
What are pathophysiology of G6PD deficiency?
X-linked recessive defect in glucose 6 phosphate dehydrogenase (an enzyme which protects cells from oxidative damage). This leads to accumulation of reactive oxygen species causing damage to cell membrane and eventual haemolysis
What are some triggers of haemolytic episodes in G6PD def?
Meds: Sulphonamides eg, sulfamethoxazole. Antimalarials, aspirin, NSAID, Dapsone.
Infections: Viral or bacterial
Fava beans (broad beans),
Chemicals,
Mental or physical stress,
Tonic water,
Soy products,
Vitamin K analogues
What are the features and investigations for autoimmune haemolytic anaemia
General features - anaemia, reticulocytosis, low haptoglobin, raised LDH and bilirubin, spherocytes and reticulocytes
Investigations - Positive direct coombs test
Describe features of warm haemolytic anaemia
Most common type. Caused by IgG antibodies.
Causes: Idiopathic, autoimmune disease (SLE), neoplastic (lymphoma, CLL), drugs eg methyldopa
Describe features of cold haemolytic anaemia?
Caused by IgM and can present with raunauds and acrocyanosis.
Causes: Neoplastic (lymphoma) or infections (mycoplasma or EBV)
Describe a direct coombs test?
Anti-human immunoglobulin is used to react with antibodies on the red blood cell surface. If positive then it indicates AIHA and HDN.
Describe an indirect coombs test
Patients plasma is mixed with donor blood. Antihuman immunoglobulin is then added to detect the presence of RBC antibodies
Whats the treatment for autoimmune haemolytic anaemia?
Cold (IgM) - Self-limiting mycoplasma infection and keep patient warm.
Warm (IgG) - Stop any drugs then give steroids, immunosuppression and splenectomy
Describe features of pyruvate kinase deficiency anaemia?
Pyruvate kinase def results in ATP depletion and then haemolysis. It presents with chronic, extravascular haemolytic anaemia
Describe features of paroxysmal nocturnal haemoglobinuria
It is caused by an acquired mutation in haematopoietic stem cells resulting in loss of surface protein which inhibits complement activation. Without this protein, RBCs are destroyes.
Presents with red urine in morning, anaemia, thrombosis and smooth muscle dystonia (oesophageal spasm or erectile dyfunction)
What is the management of Paroxysmal nocturnal haemoglobinuria
Eculizumab or bone marrow transplant
What is microangiopathic haemolytic anaemia?
Restruciton of RBCs as they travel through ciruclation. Most commonly caused by abnormal clotting which results in small thombi partially obstructing vessels and causing destruction of RBCs on their way past.
Schistocytes are key blood film finding
